The present invention relates to vehicle seats.
More specifically, the invention relates to a vehicle seat comprising a backrest and a seat part, the backrest in turn comprising:
a bottom part comprising a support frame which is pivotally mounted about a first transverse, horizontal axis of rotation by means of a pivot mechanism designed to allow a user to adjust an angular position of the backrest relative to the seat part,
and a top part pivotally mounted on the support frame about a second transverse, horizontal pivot axis parallel with the first axis, the top part of the backrest being linked to the support frame by means of a first locking mechanism designed to link the top part of the backrest to the support frame at least in an angular position of normal usage, the first locking mechanism being controlled by a first operating member to release the top part of the backrest, allowing it to pivot about the second axis, at least so as to fold it forward from the normal position of usage as far as a flat position in which said top part is disposed substantially horizontally.
Document FR-A-2 770 811 describes an example of a vehicle seat of this type.
In the known seats of this type, when the top part of the backrest is in this flat position, the inclination depends on the angular position of the bottom part of the backrest, which was adjusted by the user by means of the pivot mechanism. As a result, said flat position is poorly defined and in certain instances the top part of the backrest may be too far inclined for its rear face to be used as a tray surface under the best conditions.
The objective of this invention is to overcome this particular drawback.
To this end, the invention proposes a seat of the type in question, characterised in that:
the support frame is linked to the pivot mechanism by means of an intermediate frame pivotally mounted, relative to the seat part, about the first axis, the intermediate frame being linked to the seat part by the pivot mechanism,
the support frame is linked to the intermediate frame by means of a second locking mechanism, this second locking mechanism being controlled by a second operating member which can be displaced between, firstly, a locking position in which said locking mechanism immobilizes the support frame relative to the intermediate frame, and, secondly, an unlocked position in which the second operating member releases the second locking mechanism, enabling the support frame to pivot freely, relative to the intermediate frame, about the first axis,
the second operating member is linked to the top part of the backrest by means of a mechanical coupling device, which is designed to displace the second operating member into its unlocked position when the top part of the backrest is in its flat position and to allow the second operating member to be displaced into the locked position when the top part of the backrest is in the usage position,
and the top part of the backrest is designed to co-operate with the seat part by means of a stop when said top part is in the flat position, in order to restrict displacement of the top part of the backrest when folded forward.
As a result of these features, the incline of the top part of the backrest in the flat position is defined solely by the abutment of said top part on the seat part, so that this position does not depend on adjustments made to the pivot mechanism and can be fixed in an optimum manner.
In preferred embodiments of the invention, one and/or the other of the following features may be incorporated:
the first locking mechanism is designed to lock the top part of the backrest on the support frame when said top part is in its flat position;
the first locking mechanism comprises a catch which is mounted on a first element and which is designed to co-operate with a second element, the first and second elements being constituted firstly by the top part of the backrest and secondly by the support frame, it being possible to displace the catch between an active position in which it co-operates with the second element and a clear position in which it does not interfere with said second element, said screw being elastically biased towards its active position and being displaceable from its active position to its clear position by means of the first operating member, and the second element having two notches designed to co-operate with the catch, immobilizing the top part of the backrest respectively when said top part of the backrest is in its position of usage and in its flat position;
the second operating member is linked to a control member accessible to a user so as to displace said second operating member from its operating position, the mechanical coupling device being designed to allow this displacement of the second operating member when the top part of the backrest is in the normal position of usage;
the mechanical coupling device comprises first and second coupling members, which are slidingly mounted relative to one another between the first and second stop positions and which are linked respectively to the top part of the backrest and to the second operating member, the first and second coupling members being disposed so that the first coupling member is displaced as far as the first stop position relative to the second coupling member when the top part of the backrest is folded into the flat position, in turn driving the second operating member with it from its locked position into its unlocked position;
the mechanical coupling device is designed so that the first coupling member is in a non-operating position separate from the first stop position relative to the second coupling member when the top part of the backrest is in its position of normal usage relative to the support frame and when the second operating member is in its locked position, this non-operating position being such that the first coupling member does not drive the second operating member into its unlocked position unless the top part of the backrest has reached its flat position relative to the support frame;
the mechanical coupling device is designed so that the first coupling member is disposed in a non-operating position separate from the second stop position relative to the second coupling member when the top part of the backrest is in its normal usage position relative to the support frame and when the second operating member is in its locking position, this non-operating position being sufficiently spaced back from the second stop position to allow the second operating member to be displaced from its locked position to its unlocked position when the top part of the backrest is in its normal usage position;
the mechanical coupling device has a flexible cable which links the top part of the backrest to the second operating member, this flexible cable being disposed so that it drives the second operating member from its locked position into its unlocked position when the top part of the backrest pivots from its position of usage into its flat position relative to the support frame;
the cable is not tensed between the top part of the backrest and the second operating member when said top part of the backrest is in its normal usage position relative to the support frame, this cable being of a sufficient length so that the second operating member is not driven into its unlocked position until the top part of the backrest has reached its flat position;
the pivot mechanism comprises a rotating control member and is designed to drive the intermediate frame positively in rotation about the first axis when the control member is rotated.